Wheels are not only critical to safety in the use of an automotive vehicle, but also have an effect on vehicle stability and driving comfort.
A wheel has three main parts—hubs, spokes and rim. The hub is the center portion of the wheel, the spokes radiate from the hub to the rim, and the rim is the outer part on which the tire gets mounted. Accordingly, wheels can be one-piece, two-piece or three-piece in construction. In automobiles usage however, the nomenclature wheel parts can be segmented into rims and disc.
To maintain a reasonable cost of production as well as the necessary strength of the wheels, the parts are generally made of steel/aluminum alloys. However, wheels have an effect on the efficiency of a vehicle's performance—the greater the mass of the wheels, more energy must be imparted on the wheels to accelerate the vehicle. In order to make the wheel lighter, strength of the material is increased in raw material and/or by process.
There are different ways of making the rims and wheel discs. Usually, in the conventional method of making the wheel, the rim and discs are manufactured separately and welded together.
The most common method of making discs is using the stamping process, wherein the circular blank is cut out from a rectangular plate. After pressing to the required shape, the center portion of the material is pierced away to facilitate the mounting the wheel on the vehicle. In this process of disc making, an account of using a strip of predetermined size, substantial portion is taken away as design/engineering wastage.
Also, it must be kept in mind that typically the wheel exhibits difference in the stress pattern across the section. In the stamping process, the disc' cross section has the same thickness.
To achieve the variation in the thickness of the part, the flow forming process is followed. Though flow forming process helps to yield better wheel with reduced weight, it could not avoid the above said design/engineering wastage made during the manufacturing (stamping) process.
Therefore, there is a need in the art to provide a method of manufacturing disc which can reduce the usage of raw material, resulting in substantially less design/engineering wastage as compared to the conventional stamping process. Further, the process would enable usage of lower grade raw material that would improve the strength when manufactured into the final product.